Urbanization options evaluated 2212004a). Selecting the satellite-cities approach and determining which cities
should become nodes for urbanization were both doneaftertheurban region
had been analyzed, and areas valuable for natural systems and human uses had
been mapped. The satellite-cities approach could avoid especially valuable areas
and seemed least likely to cause significant environmental degradation. Simi-
larly, the particular satellites were chosen from the small cities present in the
Barcelona Region in part to minimize environmental problems.
In the alternative-models approach of this chapter where land of any sort
is simply covered with development, the satellite-cities model emerged as best
overall. Noanalysis of the relative value of resources and land uses across the
region was involved. The analytical approach and results of the Barcelona plan
reminds us that specific satellite cities can be chosen to minimize environmen-
tal degradation. As in the Barcelona case, satellites can also be chosen to include
distinctiveness in character and enhance economic diversity, which provide flex-
ibility and stability for the region as a whole. Finally, extensive growth around
outer satellite cities is likely to affect nearby areas outside the urban region.
Transportation-corridors model: additional dimensions
The radial transportation-corridors approach (especially without a ring
highway) may facilitate the maintenance of green wedges or a ring of parks by
ametropolitan area. Several transportation corridors, instead of a few, would
create lines of development that markedly subdivide a region. They would also
tend tocatalyze widespread fine-scale road networks supporting development,
somewhat analogous to the dispersed-sites case.
Wide strips of development along highway corridors usually degrade streams
and rivers crossing the region, and block movement patterns of certain key
wildlife species, leaving them semi-isolated in smaller sections of the region.
Overcoming these subdividing problems involves the establishment and protec-
tion of greenspaces that interrupt the strip development at appropriate inter-
vals, as well as wide underpasses and/or overpasses along the highway for the
undegraded passage of water courses and wildlife (Formanet al.2003,Iuellet al.
2003,Trocmeet al.2003). Indeed, the transportation-corridors approach poses
special problems for maintaining major greenspace corridors that interconnect
an urban region as a whole for wildlife and walkers, and that connect effectively
with adjoining regions in, e.g., the four cardinal directions.
Dispersed-sites model: additional dimensions
Results of the urbanization analyses are consistent with the awkward
or unsatisfactory component of the basic sprawl concept (Chapter1). Still, many
variants of the dispersed-sites model may occur, including: a much higher den-
sity of tiny development patches; heterogeneity in patch size; patches dispersed